package com.mla.fastdfs.utils;

import com.alibaba.fastjson.JSONObject;
import com.mla.fastdfs.commom.Result;
import org.springframework.http.HttpStatus;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.URL;
import java.net.URLConnection;
import java.util.List;
import java.util.Map;

public class HttpUtil {


    /**
     * 为response设置header，实现跨域
     */
    public static void setHeader(HttpServletRequest request, HttpServletResponse response) {
        //跨域的header设置
        response.setHeader("Access-control-Allow-Origin", request.getHeader("Origin"));
        response.setHeader("Access-Control-Allow-Methods", request.getMethod());
        response.setHeader("Access-Control-Allow-Credentials", "true");
        response.setHeader("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
        if(!request.getRequestURI().equals("/user/code")) {
            //防止乱码，适用于传输JSON数据
            response.setHeader("Content-Type", "application/json;charset=UTF-8");
        }
        response.setStatus(HttpStatus.OK.value());
    }
    /**
     * 向指定URL发送GET方法的请求
     *
     * @param url   发送请求的URL
     * @param param 请求参数
     * @return URL所代表远程资源的响应
     */
    public static String sendGet(String url, Map<String, String> param) {
        String result = "";
        BufferedReader in = null;
        String body = "";
        try {
            body = mapTobody(param);
            String urlName = url + "?" + body;
            URL realUrl = new URL(urlName);
            // 打开和URL之间的连接
            URLConnection conn = realUrl.openConnection();
            // 设置通用的请求属性
            conn.setRequestProperty("accept", "*/*");
            conn.setRequestProperty("connection", "Keep-Alive");
            conn.setRequestProperty("user-agent",
                    "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)");
            // 建立实际的连接
            conn.connect();
            // 获取所有响应头字段
            Map<String, List<String>> map = conn.getHeaderFields();

            // 定义BufferedReader输入流来读取URL的响应
            in = new BufferedReader(
                    new InputStreamReader(conn.getInputStream()));
            String line;
            while ((line = in.readLine()) != null) {
                result += "\n" + line;
            }
        } catch (Exception e) {
            System.out.println("发送GET请求出现异常！" + e);
            e.printStackTrace();
        }
        // 使用finally块来关闭输入流
        finally {
            try {
                if (in != null) {
                    in.close();
                }
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }
        return result;
    }

    /**
     * 向指定URL发送POST方法的请求
     *
     * @param url   发送请求的URL
     * @param param 请求参数
     * @return URL所代表远程资源的响应
     */
    public static Result sendPost(String url, Map<String, String> param) {
        PrintWriter out = null;
        BufferedReader in = null;
        Result result = null;
        String body = "";
        try {
            body = mapTobody(param);
            URL realUrl = new URL(url);
            // 打开和URL之间的连接
            URLConnection conn = realUrl.openConnection();
            // 设置通用的请求属性
            conn.setRequestProperty("accept", "*/*");
            conn.setRequestProperty("connection", "Keep-Alive");
            conn.setRequestProperty("user-agent",
                    "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)");
            // 发送POST请求必须设置如下两行
            conn.setDoOutput(true);
            conn.setDoInput(true);
            // 获取URLConnection对象对应的输出流
            out = new PrintWriter(conn.getOutputStream());
            // 发送请求参数
            out.print(body);
            // flush输出流的缓冲
            out.flush();
            // 定义BufferedReader输入流来读取URL的响应
            in = new BufferedReader(
                    new InputStreamReader(conn.getInputStream()));
            String str = "";
            String line;
            while ((line = in.readLine()) != null) {
                str += "\n" + line;
            }
            return JSONObject.parseObject(str, Result.class);
        } catch (Exception e) {
            System.out.println("发送POST请求出现异常！" + e);
            e.printStackTrace();
        }
        // 使用finally块来关闭输出流、输入流
        finally {
            try {
                if (out != null) {
                    out.close();
                }
                if (in != null) {
                    in.close();
                }
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }
        return Result.build("请求失败");
    }


    private static String mapTobody(Map<String, String> map) {
        StringBuffer body = new StringBuffer();
        for (String key : map.keySet()) {
            if (body.length() == 0) {
                body.append(key).append("=").append(map.get(key));
            } else {
                body.append("&");
                body.append(key).append("=").append(map.get(key));
            }
        }
        return body.toString();
    }

}
